SuperWho- What Could Have Been
by AddieWho
Summary: Surprise, surprise, the Doctor was running. Again. This time, though, he ran too far. Parallel universe? Kind of. Time travel? Somewhat. A look at what Dean is missing out on and what Castiel could be for him.


**SuperWho**

Surprise surprise, the Doctor was running. This time, he was in America. Apparently, the combination of chemicals he was using had been wrong. So very very wrong. Somehow, the Doctor had tempted a monster out of the shadows and was now being chased. _Go figure_ , he thought, _it just HAD to be a monster and not an alien or something. America._

The second he got to the tardis, the Doctor set coordinates for a location, _any_ location that wasn't this one. He had to get to the Winchesters, but first, he had to get away from the beast. The monster managed to grip the tardis so tight that the coordinates may have been a bit off. _Just as well_ , the Doctor thought, attempting to stable the rickety flight path, _there's no way that monster survive the time vortex._

Moments later, the tardis whirred to a halt, signalling her landing. The Doctor checked his screens to make sure the _thing_ wasn't out there anymore, but was shocked to hear a gunshot. _Ah,_ he thought, _The Winchesters. Right on queue._

The Doctor flew to the tardis door and flung it open, not even bothering to put his hands up, the Winchesters were old friends of his.

"Hello, Hunters! Sam and Dean! The Winchester Brothers! Never enough of you! Long time no see! Or, perhaps, for _you_ it hasn't been such a long time, but for me it has, and so I will greet you as such. "

Sam smiled just a bit, and Dean gave a glare, but neither lowered their weapons. The Doctor chose to ignore this, however, and bopped around the room, observing every detail of the dark warehouse.

"Now, where are we?" he smacked his tongue and tasted the air, "Kansas. Not quite Lawrence, but we're not too far from the bunker." The boys exchanged a knowing glance, "Topeka? Yes. Topeka."

Dean drew in a breath and was about to speak when the Doctor glided up to him and placed a finger on his lips, "No. Something isn't right." he looked at both hunters and squinted, as if attempting to analyze every pore in their skin, "This _is_ Topeka, right? Topeka, Kansas, U.S.A., Earth, Milky Way, Galactic coordinates of 5893287534001.83392….." The Doctor was cut off by the sharp clacking of a safety switch turning off.

Dean spoke as he backed away from the alien and pointed his gun directly at his forehead.

"Who are you? Where the hell did that box come from and how the fuck do you know who we are?"

The smirk on Sam's face was gone, replaced by a mix of confusion, mystery, and terror, all clouded by determination.

The Doctor had thrown his arms up in surrender, he slowly took a step back, "Dean. What are you talking about? How do you not remember me? I saved you more than once. I'm the one who helped you shave Sam's head a few years back. You invited me to your wedding!"

Dean blinked back confusion and shock, "Wedding?"

"Yes! You and Cas couldn't decide on pie or cake, so I helped make a pastry that looked like a cake and tasted like pie! wait." The Doctor took a few more steps back and sniffed the air furiously, he raced to the nearest wall and patted it, then examined the dust it left on his fingers. As he stuck out his tongue for the second time, his eyes widened.

"You're seeing this too, right?" Dean whispered to Sam.

"I wish the answer was no."

They were both interrupted by the Doctor shouting, "PARALLEL UNIVERSE. No, not parallel universe. No, timing isn't quite right, you would've met me by know. OH." his eyes fixed on the brothers, "I'm so sorry this must be very confusing for you."

The brothers both lowered their weapons, though neither could grasp the concept of _why_. This man was still a potential enemy, but his demeanor was somehow… familiar.

"Okay. Sir," Sam began, "We're gonna need you to calm down for a minute and explain yourself."

"Yes, of course. I really can't say how sorry I am. Shall I make you some tea? Coffee? Where's Cas? I have something for him."

All eyes went to Dean.

"Why are you looking at me? It's not like I keep constant tabs on him."

"However," a voice interrupted, "I am known to keep close 'tabs', as you would say, on you, Dean."

Castiel had appeared just behind the brothers, causing them to jump. A wide smile plastered itself on the Doctor's face.

"Castiel!" he announced, "Just in time! I've got a present for you!"

The Winchesters looked between the Doctor and their angel, trying to sum up the situation. Then, Cas answered.

"Thank you Doctor, but I believe you've entered through the wrong door for that."

"What?" The hunters asked in unison.

"I think it best that we sit down and explain, Doctor. May I?" the angel gestured towards the tardis.

"Of course. I'll make some coffee and we can visit a supernova while we talk."

Castiel walked in between the brothers and was about to reach for the tardis door when he turned around and found that neither Winchester was following him, "Dean. Sam. It's perfectly safe."

Sam eyed his brother. Dean eyed his angel. The Doctor rolled his eyes so far back that he was eyeing his own brain.

"Dean." Castiel stated, "Trust me."

Once Dean digested what Castiel had asked, he sighed heavily and started to walk forward. "Fine, but if this guy turns out to be trouble it's your ass that's grabbing me back from hell."

"Please, Come in." the Doctor gestured to the blue box before opening its doors, "This is the tardis. Time and Relative Dimensions in Space. That's what my Granddaughter called it, at least,"

"Wait, Granddaughter? I mean, sure you dress like the old man from Up, but you can't be _that_ old." Dean chuckled.

"Oo! Doesn't matter the time or place, Dean's still as sassy as ever!"

"Dean," Sam said, having already stepped into the blue box.

"Hold on, Sammy, What the hell do you mean, 'sassy'?"

The Doctor responded with an annoyed shrug and a sound that was probably a foreign curse word.

"Dean!" Sam said again, desperately trying to get his brother's attention.

"Sam! I said, hold on!" Dean then returned his attention to the Doctor, "Look, I don't know who you think you are, but…"

" _Dean!_ " Sam said again.

"What!?"

"Get in here."

Dean huffed as he eyed the Doctor then followed his brother's gesture toward the box. Though Sam had stopped half-way through the door, he was still amazed. He stepped further in, expecting to wake up from some Willy Wonka dream, but no such luck. Dean, however, took longer to catch on.

"Sam, I'm trying to figure out if we have to worry about this guy," Dean ranted as he entered the box and walked up to the console, "We don't know if he's a friend, a threat or just some…" Only once Dean took a minute to gesture to the large console room did he understand why his brother was so amazed. The elder Winchester ran past his brother and the strange man, and back out to the warehouse. He momentarily lost his cool running around the outer edges of the box, only to come back to the front of the box and huff.

The Doctor looked at Dean, expecting the words he'd come to love.

"Cool." Dean nodded nonchalantly.

"'Cool'? You just stepped in and out of another dimension and all you have to say is 'Cool'? Oh, nevermind, I don't really know what I expected."

"Excuse me," Sam interrupted, "Um…"

"Doctor. They call me the Doctor."

"Alright, Doctor," he continued, "What _is_ this?"

"Well, if you had been paying attention, I just told your brother that this is another dimension. Blimey, did you _not_ graduate Stanford in this universe?" The Doctor chuckled, then looked around. When he saw Sam lower his head and found a glare coming from Dean, he spoke again, "Oh. I _am_ sorry, Sam. No matter what universe, you're always the brains of the operation. Unless I'm here, but that's beside the point!" The Doctor threw his arms up and ran to the console. He poked a few buttons and looked at the hunters, "Hold on," he said, then pulled a lever and the room started to throw them around.

As the room steadied, Castiel walked out of a hallway holding a pitcher, "The water is ready. Dean, Sam, would you like some tea?"

"Oh no!" the Doctor responded, "Dean would like a black coffee with two creams and two sugars and Sam will have some of the Earl Grey that's hiding behind the mugs." The Doctor passed the two hunters, stopping momentarily to speak to Sam, "River always takes the good stuff, I've learned to keep a stash."

Dean looked at Castiel, a confused stare masking his features, "What the hell is going on!?" Castiel was about to explain, but Dean put one hand up, stopping him from continuing, "Nope. Nevermind. I don't want to know." He began walking towards the TARDIS doors.

"Dean," the Doctor spoke, "You really don't want to do that."

"No. You don't get to tell me what to do. I don't know who or what the hell you are, demon, angel,"

"Time Lord,"

"Clock King," he said sharply, "My point is, you don't know me. I don't have to do anything-" he reached for the door, preparing to grip the handle.

"Dean!" the Time Lord begged.

"No. You know what? I'm out." He pulled the handle and jerked the door open, revealing something… _new_.

Dean was taken aback. At first he was most concerned with the fact that he almost stepped into the void that stood before him, then he found himself focusing on the scene it had set.

As far as stars go, millions of them shone bright. The colors of the galaxy began with blue coated in a silver that turned into a constant. Pink clouds formed a ring around an expanse of the galaxy, showcasing it as if it were a stage. Dark purple formed the velvet curtain of the theatre, radiating a welcoming feeling. Light teemed from everywhere, dripping from the diamonds strewn around the sky.

The hunter's thoughts were interrupted by the Doctor stepping in front of him and closing the door with his entire body. Dean stood still for a few moments of crippling silence.

"I can explain." the Doctor spoke carefully. But before he could, the entire room descended into madness again as they heard Cloister bells chime. Dean nearly fell to the ground, finding safety only in the railing he had found. Sam had done the same, dropping to his knees. Castiel, on the other hand, was standing perfectly still. He looked at the Doctor with more a sense of annoyance than anything else.

As the Doctor raced around his living machine, he gaped, "Oh! Yes, landing," the Doctor was thrown a few feet from his console, "alright, I'll put you in spy-mode. Vision fields: rising, Silencer: Powered, Organ lock: Sustained." the room began to shake even more as the Doctor analyzed what was on his screen, "That makes more sense! That was my second guess," a large jerking motion appeared amongst the clatter, "Alright! My third guess!" after a few buttons, a lever or two, and some taps on the screen, the TARDIS came to a halt.

"Doctor." Castiel's voice was thick and brooding.

"It's alright, Cassie!" he responded, "I'm back in my universe! Home again, home again! Wow, I was worried there for a moment."

"Wait," Sam spoke, regaining his balance, "We're back in _your_ universe?"

"Yes! Isn't that great!"

"Well, for you, yeah, but, _we_ ," he gestured to his friends, "need to get back to _ours_."

"Aaaahhhh." The madman said, realizing his problem, "Alright. No problem! I've just got to refresh the intra-particle thingamabob and fix the spinny thing that's shaped like an apple. Shouldn't take too long."

The Winchesters exchanged confused glances before the angel spoke up, "Doctor, I'm going to peek out and make sure it's safe.

"Be careful! I've no clue where we are! Because you're from a different dimension, if somebody is out there, they won't be able to see or hear you, but they will be able to see the inside of the TARDIS. So, leave the door closed."

"Of course, Doctor." Castiel opened the door just a crack, then proceeded to open it further until he could see outside. As he peeked around the corner of the door, he paused. A few seconds later, he stepped back inside and slammed the door.

"Cas, buddy, what's wrong?"

"Nothing!" Cas responded a little too quickly.

Dean observed his angel. The color had drained from his face, making him look sickly. His eyes were wide and… watering? Was Castiel, angel-of-the-lord Castiel… tearing up?

"Castiel?" The Doctor asked, from his position at the console "Are you alright? What's wrong?" Apparently, the angel's mood was noticeable. All three of Cas's friends were looking at him with concern.

Castiel tried to compose himself. He stood straighter and looked at the Doctor, "Yes. I'm fine."

"What's going on out there?" He asked.

"NOTHING. We are completely safe, Doctor. Nothing dangerous at all."

Dean's eyes bore into Cas's, asking inaudible questions that only they shared. Eventually, Dean huffed and started to walk towards the trench coat.

"No." The angel spoke, blocking the hunter's reach to the door. Another pitiful gaze was exchanged, "Please…"

Dean looked at him with concern. After placing a comforting hand on his angels shoulder, Dean opened the door.

As far as Dean could tell, it was just a plain old room. A window, a door, a bed with the blankets crumpled. No light came from the window, so it must have been night. It seemed so plain. Like every other room Dean had seen. An ease of familiarity wafted through him as he stepped outside of the box.

"Dean," Castiel broke out of the box, followed by the Doctor.

As Castiel turned to the time lord, he looked concerned, "Doctor," he whispered, "Won't he be able to see you?"

"No." the Doctor responded at full volume, "He can't hear me either. I've got some cloaking candies. They taste like old textbooks, but they serve their purpose."

"What do you mean, ' he'?" Dean asked. He turned back to the room that had become more familiar than ever, "There isn't anybody in-"

The Doctor held up his forefinger, successfully shushing the Oldest Winchester as Sam came to join them. They all went silent, listening carefully to their surroundings. Nothing could be heard. Then, a soft humming filled their ears.

Dean's eyebrows knit, attempting to locate the song could be identified as some softer version of Carry on my Wayward Son. A silhouette faded in from one of the darker corners of the room, walking and swaying. It was easy to deduce that the humming was coming from this figure. As the shadowed man stepped into the light, they were all shocked to find that it was Cas. _Holding a baby._

Sam looked from the Cas that he knew, trenchcoat and all, to the Cas from the other universe, wearing an old faded t-shirt and loose pajama pants. _That_ Castiel was softly smiling, eyes tired, but happy. _Their_ Castiel had watering eyes. His gaze shifted between the other Cas, Dean, and the floor. The Doctor grew silent, trying to find a way to comfort Dean and Cas without digging too deep into their stained-glass situation. One touch, the Doctor feared, would shatter whatever was left of the two.

This was the Doctor's universe. This is the one he had come to know. He had to get them out of there, _now._ Or, at the very least before-

The sound of a door opening filled the room. _Too late,_ the Doctor thought. As the door opened, light poured into the room, causing the baby to cry.

"Hey! Come on!" the other Cas said, "You could have at least turned off the hall light. Celeste was almost asleep!" he chuckled, a figure obscured the light.

"Sorry, Cas. I just warmed up a few bottles. Jude was getting fussy, so I figured they might need to eat."

There was no mistaking that voice. Booming, yet gentle. Soothing, yet strong. That was the voice of Dean Winchester.

The travelers, Dean, Sam, Cas, and the Doctor, all backed towards the TARDIS, making room for the carnival mirrors in front of them.

"Okay, what the hell is going on!" Dean yelled, obviously confused by the off putting scene put before him.

"I swear I can explain!" the Doctor said, turning to the TARDIS, "But, first, we need to get back inside before you all see something you aren't supposed to see."

Again, the Doctor had spoken too late, as the figure came closer to the other Cas, it became quite obvious that two people were walking in. _That_ Dean was holding another baby, almost identical to the first. Before they knew what was happening, the travelers saw the other Dean lean in and kiss the other hunter over a cooing baby.

They were interrupted by a tune coming from nowhere. As they all looked at each other, they quickly found that the source of the music was erupting from the pockets of the bathrobe worn by the _other_ Dean. He picked it out of his pocket quickly, then set down baby Jude in his crib.

"Hey, Lexi!" he said.

The Present Sam looked to the Doctor, "Who's Lexi?"

"Okay, We'll see you guys soon," Other!Dean said as he hung up the phone and looked to his Cas.

The other Cas raised his eyebrows, "Has he asked her yet?"

"No!" Other!Dean said, "He's going to ask her over dinner, Cas! Why else would I be cooking a huge meal in the other room?"

Other!Cas just laughed, "Speaking of, do you smell something burning?"

"That's not funny, Babe!" he responded, followed by his nose whiffing the air. He then rushed out of the room, leaving no explanation except something along the lines of, " _My Pie!"_

The Doctor leaned to his group of wary travelers, "We really ought to be getting inside. We can watch the rest on the monitor. I won't be invisible for long." He opened the door, followed by Sam. Castiel was halfway through the door when he noticed Dean was not following. Instead, the Present Winchester started to step closer to the Other!Cas. He stood, looking at the two babies, Celeste and Jude.

Other!Cas's words were barely audible, "Don't fuss, my small humans. Your father's will love you until the end." He gently put the little girl down in an adjacent crib and walked out of the room, leaving on a small light.

"Dean?" Present Cas put his hand on Dean's shoulder. The hunter slowly turned around and walked directly to the box that had brought him here.

As he stepped in, he found the Doctor, "Alright, Time King," he began.

"Time _Lord_ ," the Doctor interrupted.

"I don't care. Whatever you are, Doctor, you have ten seconds to explain to me what I just saw before I mess you up until your head is so far off up your butt that your stupid bowtie would replace your underwear."

All the eyes in the room stared at Dean, obviously processing what they just heard. After a few moments of silence, Dean continued, "Starting now."

"Now?" the Doctor asked, "this seems like a bit of a tight time frame, you don't think…"

"5,"

"But really, it's much harder to explain than all that-"

"3"

"Would you just-"

"2,"

"No, really, Dean,"

"1,"

"Why don't we just sit down and-"

"0," Dean started to charge towards the Doctor.

"ALRIGHT," the Doctor yelled, taking a deep breathe, "Outside that door is the universe that _I_ came from. It's akin to a parallel universe except, rather than a single decision changing the world, it's two. As far as I can tell, _this_ universe is a cross of the one where Dean and Cas have gotten married and adopted twin children, and Sam finished his time at Stanford before traveling and killing monsters and 'Saving people, hunting things, the family business'. Not only that, but I'm fairly positive that _your_ universe doesn't involve Lexi. She was introduced to Sam by one of his college friends after Jess died in a drinking and driving accident during his senior year of University. When he left to help you find your father, she insisted on coming along and learning the hunting life, and Sam and her are now dating." he took a breathe, "See? It's really very simple."

Silence swept over the room as the Doctor lowered his guard and Dean's face dropped, "So," Dean spoke, "You're telling me that, _that_ ," he pointed to the door, " _that_ , could have been _my_ life?"

"Yes, Dean,"

"Doctor," Castiel's tone came as a warning to the Doctor.

"In some ways, it still could be." he said gently, "I'm so sorry. You weren't meant to see that."

"No. Just, what do you mean, 'it still could be'?"

"Doctor!" Cas tried to stop the alien from continuing. He only managed to hold his attention for a moment, though.

"That's really not my secret to tell," he continued.

"Then whose is it?" Dean asked.

" _Doctor!_ " Castiel shouted, drawing the attention of everyone in the TARDIS.

Dean turned to his angel, "Cas?" the hunter breathed hard, "You- you _knew_?" Dean's green eyes dug their way into Castiel's, pleading for… something. He didn't know what.

Castiel's face fell to the ground, "Yes. I started to explore these other universes quite some time ago. Really, I became curious once I realized-"

"Realized what, Cas?"

The Angel responded with teary eyes and a tilted head. His face became some pathetic mixture of confused and grieving. His eyes closed, along with his mouth, unable to find the right words. Finally, he spoke softly, "Please. Don't make me say it."

Dean stepped closer to Castiel, trying to get a better look at his angel. With each step, he found himself more eager to be close to him. Before Castiel could pry his eyes open, Dean's lips crashed into his.

The kiss was deep and passionate. A few moments felt like a millennia before they separated. Dean's nose found his partner's for balance as his lips drew back. They stared at each other with wonder in their eyes before Dean started to chuckle, his happiness being cut off by Castiel pressing his own lips to Dean's.

Soon they found themselves in a bubble, cut off from the rest of the world. The TARDIS could be on fire, a vampire could be sucking Sam's blood, The Doctor could be having a Hearts Attack, and none of it would matter. Nothing mattered except that they finally found each other. They had waited long enough. Now that they knew what the other was feeling, there was nothing in their way.

They were only interrupted by the TARDIS shaking violently, bringing them both to the ground, laying next to each other, wondering how long they had been together.

"I've done it!" The Doctor shouted, successfully grabbing the attention of the hunters, "Sam, Dean, Castiel, welcome home!"

The TARDIS doors flew open, showing the travelers the bunker from their own universe.

"Is that it?" Dean asked, having stood up. He reached his hand out to help Castiel stand and was met with a kind gaze, "Do we just go back now?"

"I suppose," the Doctor seemed confused, "Yes. I suppose you do. Again, I really must apologize for the inconvenience."

"But, wait, Doctor," Sam asked before following his brother's lead out of the box, "Are you in this universe too?"

The Doctor smiled widely, "Of course! I'm a Time Lord! You can't get rid of me that easily! I'll tell you what," The alien dug around in his pockets for a moment, then pulled out a strange looking piece of metal with some sort of a light at the end, and handed it to Sam, "It's called a Sonic Screwdriver. Once you get out there, get onto the roof of the bunker and point it directly at the sky. Think of me and press the button, I'll be there before you get the chance to say, 'What the hell is this thing!',"

Sam took it gratefully, then gave a sad glance at the TARDIS. He smiled a sad smile and turned to leave.

"She's still out there, you know?"

"What?" Sam asked.

"Lexi. The night that we just saw, back in my universe, you were going to propose to her."

Sam looked at the Sonic screwdriver with large eyes and a melancholy smile, "I don't think it'd be the same." he said.

"Well of course it won't!" the Doctor exclaimed, "Nothing is going to be the same as it was back in _my_ universe! You can't just copy and paste, it doesn't work like that!" Sam was taken aback, "But," the Doctor continued, "Lexi _is_ still a hunter. Some people are just destined to be something. I would bet every ounce of money I don't have to say that there is _no_ safe universe out there where Sam and Dean Winchester, Castiel, and Lexi weren't hunting. Together or not. It's simply the way you were programmed."

"Are you telling me I could still find her?"

"Oh, absolutely not!" Sam gave a look of mixed confusion and anger. The Doctor continued, "You, Samuel Winchester, are _not_ going to be able to find Alexis Courtney Lorde hunting down monsters in the busy streets of Los Angeles. You _won't_ save her life on a hunt, and you definitely will _not_ find her camped out at her grandmother's house on 628 E 27th Street."

Sam's face perked up, "What?" he said in a flash of joy and confusion.

"Oh, you always were clueless," the Doctor said as he pulled a business card out of another pocket. He handed it to the Winchester, showing him red writing on it, "That's all the information you'll need to find her. Go easy, though. You didn't get that from me." He smiled, and Sam mirrored his expression.

"Thank you, Doctor." he said, "I think we would have become good friends."

"Oh, Sam." he responded, "I think we already have."

Then, the Doctor left. The wheezing of the TARDIS echoed through the halls of the bunker. It's widely known that, if the Doctor should show up on your doorstep, your entire world would change. However, with Dean and Cas longing for each other, Sam's heart in his throat, and a sonic screwdriver ready for adventure, the Winchesters couldn't help but feel that their world was only beginning to change.

 _ **I hope you enjoyed it! If you liked Lexi, you can read more about her in another one of my fics 'A Hunter's Heart". Share around and don't forget that Comments give me life!**_


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